The present invention relates to a fuel injector for a gas turbine engine, more particularly such a fuel injector having two fuel injection paths supplied by a common fuel supply conduit.
The performance of a combustion chamber for a gas turbine engine is directly related to the features of its fuel injector, namely the size of the fuel particles, as well as the spatial and radial fuel distribution. These features vary widely, depending upon the operating mode of the gas turbine engine, thereby making it increasingly difficult to achieve desired engine performance for all engine operating modes.
The proportion of air and fuel injected into the combustion chamber usually involves tradeoffs between engine performance under full power conditions, and engine performance at low power conditions. Reignition of the engine at altitude and the increasing demands for controlling harmful emissions from the engine have increased the considerations in fuel chamber/fuel injector design. Accordingly, the use of single, fixed geometry fuel injectors has resulted in an increasingly more difficult tradeoff between the various operational parameters of the gas turbine engine.
At present, engines are fitted with aerodynamic injectors improved by variable geometry devices to continuously match the air proportion to the engine's operational mode by means of movable elements acting as diaphragms for the combustion chamber air intakes. However, the aerodynamic injector has a low efficiency for low power operations.,
Fuel injector systems have been designed to incorporate mechanical as well as aerodynamic injectors in which the mechanical injector operates under low power operating conditions, while the aerodynamic injector operates at medium and full power conditions. A typical example of such a design can be found in French patent 2,665,729. However, these types of injectors, which use separate fuel supply conduits for each of the injector types, requires a significant amount of time to fill the fuel feed paths and to switch between the different types of fuel injectors.